Related Coverage

BOSTON (AP) — Friends of Boston Marathon bombing suspect Dzhokhar Tsarnaev became involved in the investigation into what happened after a signal from his cellphone while he was a fugitive was transmitted from their apartment, an FBI agent testified in federal court on Tuesday.

Special agent John Walker said that the FBI had strong evidence to believe that Tsarnaev was hiding out April 19, 2013, in his college friends’ apartment in New Bedford, about 60 miles from Boston and not far from the University of Massachusetts Dartmouth campus. Tsarnaev was registered to three other cellphones.

Walker also said that Tsarnaev had used one of the friends’ Skype accounts to make several calls a few days after the April 15, 2013, attack, which killed three people and injured more than 260 others.

The friends, Azamat Tazhayakov, Dias Kadyrbayev and Robel Phillipos, will be tried separately in Massachusetts.

Federal Judge Douglas Woodlock ruled Tuesday that Tazhayakov will stand trial on June 30, followed by Kadyrbayev on Sept. 8 and Phillipos on Sept. 29.

Their lawyers had asked the judge to move the trials out of state because of the overwhelming media coverage around the case.

The judge said the defendants could receive fair trials in Boston or in Springfield, 80 miles west. He pointed to the trial of Boston mobster James “Whitey” Bulger, which was held in Boston despite its high profile.

Kadyrbayev and Tazhayakov, who are Kazakhstan nationals with expired student visas, are charged with tampering with evidence for removing Tsarnaev’s laptop and a backpack containing fireworks from his college dorm room shortly after last year’s fatal bombing, in which pressure cooker bombs exploded near the marathon’s finish line. Kadyrbayev also faces conspiracy and obstruction of justice charges. He and Tazhayakov have been held without bail for more than a year.

Phillipos, of Cambridge, is charged with lying to investigators. He has been held under house arrest.

Each of the friends has pleaded not guilty.

Kadyrbayev is expected to take the stand Wednesday in an effort to suppress evidence in his upcoming trial. He was questioned without counsel and underwent a lengthy and strenuous interrogation, and officers searched his apartment without a warrant, said his attorney, Robert Stahl.

Walker said the defendant spoke to him voluntarily and signed a document stating FBI agents could search the apartment.

Tsarnaev, 20, has pleaded not guilty to 30 federal charges related to the deadly bombing. His brother, Tamerlan Tsarnaev, 26, died after a gunbattle with police three days later, the night Massachusetts Institute of Technology security officer Sean Collier was shot and killed. Dzhokhar Tsarnaev is facing state charges in Collier’s death.

Federal prosecutors are seeking the death penalty in Tsarnaev’s trial, set to begin in November.